I think the web really killed the idea of "native" widgets. I think the rise of web apps just got everyone used to the idea that controls are just going to look different everywhere. Even on macOS, practically every app I use has a very distinct look and set of widgets (vscode, photoshop, blender, spotify -- two of those are electron, but even the non-electron stuff doesn't look very much like a "mac" app anymore). A…
I think it's more a desire for branded UI rather than Web apps. Adobe wants their UIs to be instantly identifiable as Adobe, Slack wants to be instantly identifiable as Slack, MS Office as you said, etc. Personally, I doubt this benefits users (do you really need to market to people who already bought your product?) but I'm sure the logic is compelling to decision makers and it's cheaper to "design once, run everywhe…
When operating a Mac I expect Mac-specific behaviors. When operating a Windows PC I expect Windows-specific behaviors. I LOATHE programs that decide to do away with OS-isms that I am accustomed to and require me to learn how to "do things their way" because they wanted cross-OS consistency. Sometimes this means conforming everything to a single platform which is partially evil but just as often it means conforming to _none of them_ which is pure evil.
But I understand this - as a web developer I've experienced pressure from Project Managers and the "decision makers" to make things consistent across browsers/devices even if doing so goes against how the users of said browsers/devices would expect things to operate - breaking user expectations and creating a worse UX for many users. I fight against it when I can but I'm not always successful.